Encapsulation of powders



May 27, 1969 M. K. MEHTA 3,446,404

ENCAPSULA'IION OF POWDERS Filed Jan. 15, 1968 Sheet of 7 y 7, 1969 M. K.MEHTA ENCAPSULATION 0F POWDERS I Filed Jan. 15, 1968 Sheet 5 of? M m wwm Wm m A M M 27, 1969 M. K. MEHTA 3,446,404

ENCAPSULATION OF POWDERS Filed Jan. 15, 1968 Sheet 3 of 7 May 27, 1969M. K. MEHTA 3,446,404

ENGAPSULATION OF POWDERS Filed Jan. 15, 1968 Sheet 4- of? MflH/WIJMew/EN MEHTA Z WWPZW ATTOKA/f Y5 May 27, 1969 M. K. MEHTA 3,446,404

ENCAPSULATION OF POWDERS Filed Jan. 15, 1968 Sheet 5 of 7 Aime/VH5 M. K.MEHTA ENCAPSULATION OF POWDERS May 27, 1969 Sheet 6 of '7 Filed Jan. 15,1968 US. Cl. 222-225 12 Claims ABSTRACT OF THE DISCLOSURE A rotary feedroll for filling gelatine capsules with powder from a hopper, the rollbeing covered with a rubber sleeve which is drawn by suction intoopenings in the surface of the roll to form charge chambers for thereception of the powder, the rubber sleeve being covered with anapertured metal sleeve to protect the rubber sleeve against damage andfacilitate rotation of the roll across the mouth of the hopper. Uponrelease of the suction the charges are ejected by the resilience of therubber sheet. This resilience, aided by air pressure in place of thesuction, may be used to compress the charges against a backing platecovering the mouths of the charge chambers. The size of the chargechambers may be varied by variation of the degree of suction, or byproviding an element within each opening to limit the penetration of theelastic sheet.

This application is a continuation-in-part of my copending applicationSer. No. 614,323, filed Feb. 6, 1967, now abandOned.

The invention relates to dispensing apparatus for powdered or granularmaterials which comprises a hopper and a rotary feed roll closing themouth of the hopper and having openings in its periphery to receivematerial from the hopper and convey it to a discharge position.

Apparatus of this kind is used particularly for filling gelatinecapsules with pharmaceuticals. For example, British patent specificationNo. 881,022 describes apparatus in which capsules are formed by bringingtogether two capsule-halves formed in two strips of gelatine or the likewhich pass round two revolving die rolls having matching die pockets intheir surface to which suction is applied to form the capsule-halves.The capsule-halves formed on each die roll are filled with the aid of afeed roll mounted directly above the die roll and having charge chambersin its periphery which are filled with powder from a hopper and fromwhich the powder is ejected into the formed capsule-halves.

In that specification each of the charge chambers contains acam-operated plunger for ejection of the charge at the dischargeposition. This plunger forms the base of the charge chamber and must fitclosely to prevent entry of powder between the plunger and the walls ofthe chamber. The accurate construction and fitting of these plungers ineach of a large number of individual charge chambers increases thedifiiculty and cost of manufacture and maintenance of the apparatus.

It is an object of the present invention to provide improved dispensingapparatus which does not require accurately constructed and fittedplungers.

British patent specification No. 394,489 describes another form ofdispensing apparatus for moulding substances such as confectionery. Thisform of apparatus has a sheet of elastic material covering a roll havingmoulds in its periphery. The moulds are adapted to be raised out of theroll up to the mouth of the hopper when they are to be filled. Suctionis applied to the moulds in order to 3,446,404 ?atentecl May 27, 1969draw the sheet of elastic material into them. This apparatus has thedisadvantage that it is slow due to the necessity for raising the mouldsout of the feed roll for filling, which requires the feed roll to berotated discontinuously. In addition the sheet of elastic materialsufiers great deformation when the moulds are raised up to the mouth ofthe hopper, and thus must be relatively thick to withstand the repeateddeformation. However, the thicker the sheet of elastic material is, theless accurate will be the volume of material dispensed by the apparatus.Thus this form of apparatus is not used for accurate measurement such asis required in pharmaceutical applications.

It is an object of this invention to provide a feed roll which canemploy a thin sheet of material so that the volume of material dispensedis sufiiciently accurate for pharmaceutical purposes, and which can beoperated quickly and continuously.

The present invention exploits the use of a feed roll having a sheet ofelastic material covering openings in the periphery of the feed roll. Asleeve fits closely over the sheet of elastic material and has aperturesregistering with the openings in the feed roll. The apparatus appliessuction to the openings to draw in the sheet of elastic material andthereby form charge chambers to receive charges of material from thehopper, and releases the suction to cause ejection of the charges at thedischarge position.

In this way the walls of each charge chamber are formed by the elasticsheet and thus present a continuous barrier to the passage of powderinto the interior of the feed roll. The elastic sheet is easily fittedto the feed roll and a single sheet can cover all the openings in thefeed roll. The elasticity of the sheet effects ejection of the chargeswhen the suction is released.

The apertured sleeve serves to protect the elastic sheet against damageand to enable a close fit to be maintained with the mouth of the hopperwhile allowing the feed roll to rotate smoothly. The apertures in thesleeve define the mouths of the individual charge chambers.

The mouths of the charge chambers can be covered in known manner duringtheir passage from the hopper to the discharge position either by astationary plate or by a flexible charge retention sheet stretchesaround the periphery of the feed roll or by a combination of theseelements. If the suction is released while the mouth of the chargechamber is covered by a stationary backing plate the elasticity of thesheet will tend to compact the powder into a slug. This may be assistedby the application of pneumatic pressure in place of the suction. Suchpressure may also be used to assist the ejection of the charge.

Controlled application of suction to form the charge chamber while theopening in the feed roll is under the mouth of the hopper will assist indrawing the powdered or granular material into the charge chamber andensuring complete filling of the charge chamber, thereby enablingaccurately-measured quantities to be dispensed. The size of the chargechamber can be varied at will by changing the degree of suction applied.

However, when using this method of varying the volume of the chargechambers, it is found that it is not possible to control the volume ofthe charge sufiiciently accurately for some applications, for examplefor use with certain pharmaceutical products. Also it is difiicult tohandle materials which are not free-flowing, as the suction createdbetween the elastic sheet and material resting on the feed roll is notsufiicient to fill the charge chamber.

When using the apparatus to dispense such materials, it is sometimesfound convenient to employ a modified form of the apparatus whichincludes an element within each opening in the feed roll which ismovable within the opening to limit the depth of penetration of theelastie sheet into the opening on the application of suction.

The feed roll may have an axially movable core, and the said elements soengaging with the core that axial movement of the core causes movementof the elements in a generally radial direction in the feed roll tocontrol the positions of the elements.

The invention will now be described in more detail with the aid ofexamples illustrated in the accompanying draw ings, in which:

FIGURE 1 is a front view, partly in section transverse to the axis ofthe feed roll, of dispensing apparatus in accordance with the inventionforming part of a machine for manufacturing filled gelatine capsules,

FIGURE 2 is a side view, partly in section, of part of the apparatusshown in FIGURE 1,

FIGURE 3 is a View similar to FIGURE 1 showing a modified form ofapparatus,

FIGURE 4 is a detail of the valve plate used in the apparatus of FIGURE3,

FIGURE 5 is a front view of a further modification,

FIGURE 6 is a view similar to FIGURE 1 showing another modified form ofapparatus, and

FIGURE 7 is a side view, partly in section, of part of the apparatusshown in FIGURE 6.

The apparatus of FIGURES 1 and 2 has a hopper 10 in which the powderedor granular material 11 is held and maintained in a free-flowingcondition by an agitator 12. A sliding closure plate 13 enables thebottom of the hopper to be closed when the machine is taken out ofoperation. A feed roll 14 is mounted on a shaft 15 for rotation about ahorizontal axis below the mouth of the hopper 10. A number of openingsor cavities 16 are formed in the periphery of the roll 14. The surfaceof the feed roll is covered by an elastic sheet 17 in the form of acylindrical sleeve fitting over the roll and covering the openings 16.Over the elastic sheet 17 is a thin metal sleeve 18 having aperturesregistering with the openings 16 in the feed roll. At the mouth of thehopper 10 a seal 19 engages the surface of the sleeve 18 to preventescape of powder from the hopper while allowing the feed roll 14 torotate, carrying with it the sleeve 18.

The openings 16 in the periphery of the roll 14 are arranged in rowsparallel to the axis of rotation of the feed roll, as shown in FIGURE 2,and the openings in each row are staggered relative to those in adjacentrows. The openings of each row communicate through radial holes 20 witha common axial passage 21 to which suction can be applied to draw theelastic sheet 17 into the openings 16 and thereby form charge chambers22 lined by the elastic sheet, which receive charges of powder from thehopper 10. The roll 14 rotates in an anti-clockwise direction (as seenin FIG. 1) to carry the powder which enters the charge chamber 22 at itstopmost position a to the lowermost or discharge position b. A chargeretention sheet 23 prevents the loss of powder from the charge chambersuntil they reach the discharge position. Here the charge is deliveredinto a preformed capsule-half 24 shaped from a gelatine sheet 25 on adie roll 26 by the application of suction through a passage '27.

The elastic sheet 17 is a sleeve of latex rubber and has a thickness ofabout .010 inch. It is held in place at each end by a retaining ring 28disposed in a groove 29 (FIG- URE 2). The sleeve 18 is a thin stainlesssteel sleeve which is secured to the feed roll 14 by screws 30 at oneend of the roll and locating dowels 31 at the other end.

The application of suction to the passages 21 is controlled bystationary valve plates 32 at each end of the feed roll 14. Each valveplate 32 has an arcuate vacuum groove 33 extending from the fillingposition a round to a position before the discharge position b. Thevacuum groove 33 is connected by a conduit 34 to a vacuum line and whilethe ends of each passage 21 are in register with the vacuum groove 33suction is applied to the individual openings 16 to draw the elasticsheet 17 inwards and thus form the charge chambers 22.. At the discharge7 position b the ends of the passages 21 come into register withejection pressure holes 35 in the valve plates 32 which communicatethrough conduits 36 with a pressure source. The pressure thus applied tothe openings 16 assists the elasticity of the sheet 17 in ejecting thecharge from the charge chamber into the capsule-half 24.

As shown in FIGURE 1 the charge retention sheet 23 is secured at itslower edge to a bar 37 on which is mounted a plate 38. The edge of theplate 38 defines the discharge position, the sheet 23 passing round thisedge on to the surface of the feed roll and being attached at its upperedge to a rotatable bar 39. The bar 37 is hinged to allow the plate 38to swing and the bar 39 is biased by a spring 40 acting on an arm 41 tomaintain the sheet 23 in tension against the periphery of the feed roll.The charge retention sheet 23 can be a single or double layer of Wovenmaterial, for example two layers of cotton fabric or a layer of cottonfabric backed by fine wire mesh.

FIGURE 3 shows a modification of the apparatus of FIGURES 1 and 2.Corresponding parts in the three figures have been given the samereference numerals and it will not be necessary to describe again thoseparts of the apparatus of FIGURE 3 which are the same as that of FIGURES1 and 2. In FIGURE 3 the charge retention sheet 23 extends over asmaller area of the surface of the feed roll 14 and is preceded by abacking plate 42 attached to a rotatable rod 43 and biased against thesleeve 18 forming the surface of the feed roll by a spring 44 acting onan arm 45. The valve plate 32 has a short suction groove 46 in theregion of the mouth of the hopper 10, a compression pressure hole 47 atthe position 0 where the mouths of the charge chambers are closed by thebacking plate 42, and a longer arcuate suction groove 48 extending fromthe point d where the charge chambers pass under the charge retentionsheet 23. By the application of air pressure through the hole 47 thecharge of powder in the charge chamber is compressed between the backingplate 42 and the elastic sheet 17. The elasticity of the rubber sheetwill effect some compression when the suction is released but preferablythis compression is increased by the application of air pressure to theextent necessary to form the powder into a slug which will be coherentwhen ejected into the formed capsule-half 24 but sufficiently fragile tobreak up when the capsule takes its final shape.

The slug ejected at the discharge position falls into the preformedcapsule half 24. The filled capsule half is brought into register with asimilarly-filled complementary capsule half on a second die roll and thetwo capsule halves are united as described in British patentspecifications Nos. 881,022. and 957,840. The two slugs in each capsulebreak up under the pressure exerted by the walls of the capsule duringits formation and during subsequent tumbling of the capsule. Thecompaction of the powdered material nevertheless facilitates filling ofthe capsules and enables a greater weight of material to be enclosed ina given size of capsule. The shape of the slug may be changed byaltering the transverse cross-section of the charge chamber so that theslugs are suitable for encapsulation in round, oval or oblong capsules.

FIGURE 4 shows the details of the construction of the valve plate 32 forthe embodiment of FIGURE 3. The grooves 46 and 48 are connected byconduits 49 to the vacuum source while the holes 35 and 47 are connectedby conduits 50 to the pressure source. To avoid any leakage ofcompressed air across the valve plate into the vacuum grooves, radialchannels 51 are formed in the valve plate which communicate at each endwith the atmosphere.

FIGURE 5 shows in outline a further modification in which thecompression of the charges is effected immediately before their ejectionfrom the charge chambers. As in FIGURE 1 the charge chambers afterleaving the hopper 10 pass directly under the charge retention sheet 23and suction is maintained by the groove 33. The lower edge of the chargeretention sheet 23 is attached to a block 52 which presents a backingsurface 53 engaging the periphery of the feed roll in the position 0.Here a pressure hole 54 is provided in the valve plate 32 and pressureis applied to compress the charge. On reaching the position b pressureis again applied through the hole to eject the compressed charge.

The apparatus shown in FIGURES 6 and 7 is a modified form of theapparatus described with reference to FIGURES 1 and 2. Correspondingparts have been given the same reference numerals and it will not benecessary to describe again those parts of the apparatus of FIG- URES 6and 7 which are the same as that of FIGURES 1 and 2.

The apparatus illustrated in FIGURES 6 and 7 has improved means foradjusting the volume of the charge chambers 22, to permit more accurateand hence economical dispensation of the powder or granulated material11. The extent to which the elastic sheet 17 can be drawn into theopenings 16 when suction is applied is controlled by flat-headed pins60, which are movable with the openings 16 to limit the depth ofpenetration of the elastic sheet 17.

As is illustrated in FIGURE 7, the feed roll 14 has a close-fittingshaft or core 61 which is adjustable axially within a small range bymeans of a knurled bolt 62. A spring 63 tends to push the core upagainst the inner end of the bolt 62. Rotation of the bolt 62 causes thecore 61 to move axially to left or right as seen in FIG. 7.

The fiat-headed pins have cone-shaped inner ends 64 which engage incone-shaped depressions or holes 65 in the core. As shown, the innerends 64 of the pins fit fully into the depressions 65. If the core 61 ismoved axially to the right by means of the bolt 62, the pins 60 will becaused to rise out of the depressions 65, and thus to decrease thevolume of the charge chambers 22. Thus it can be seen that the volume ofthe charge chambers is continuously adjustable over a limited range.

The openings 16 are circular in cross-section, although other shapes,for example, oval and oblong, may be used. The pins 60 fit inside theopenings 16 with a small clearance between the pins and the sides of theopenings to allow the vacuum applied to the passage 21 to reach theelastic sheet 17.

The apparatus illustrated in FIGURES 6 and 7 also has improved means foragitating the material in the hopper.

The hopper 10 contains a number of scrapers or wiper arms 70. These aresupported from a frame 71 and carry wiper shoes or blades 72. The frameis reciprocated from left to right (as seen in FIGURE 7) by means of acam 73 on a shaft 74 which may conveniently be connected to the shaft15, preferably through gearing, for rotation by a common motor. The cam73, which is a skewmounted disc, runs between two pins 80 and 81 on theframe 71 to effect movement thereof. The movement of the frame causesthe wiper shoes to reciprocate transversely across the surface of thefeed roll, and thus to sweep material into the charge chambers 22. Italso serves to agitate the material in the hopper, which additionallyassists in proper filling of the charge chambers and thus helps tomaintain consistency of the volume of the charge. The use of the wipershoes makes it possible to handle powders which are substantially notfree-flowing.

The hopper side walls contain screws 83 for adjusting the pressure onthe seal 19 on the feed roll independently of the position of thehopper. The screws are threaded into holes 82 in the walls of the hopper10.

While the specific embodiments have been described as forming part of aparticular known form of encapsulating machine it will be apparent thatthe dispensing apparatus in accordance with the-invention may be used inother forms or" encapsulation machine Whether for filling capsules inprocess of formation or preformed capsules.

Moreover the apparatus can be applied to the filling of bottles,ampoules, packets and other containers.

The specific embodiments show two valve plates, one at each end of theroll, to ensure uniformity of pressure in the charge chambers in eachrow. With shorter feed rolls a single valve plate will sufiice.

The means employed for retaining the charges in the charge chamber up tothe discharge or delivery position may be of any known type and may, forexample, consist of a rigid housing surrounding the periphery of theroll.

I Claim:

1. Dispensing apparatus for continuously dispensing powdered or granularmaterials, comprising:

a hopper, a rotary feed roll having a portion of its periphery closingthe mouth of said hopper, said feed roll having openings in itsperiphery to receive material from said hopper and convey it to adischarge position, a sheet of elastic material covering said openingsand normally positioned adjacent the periphery of the roll, a sleevefitting closely over said sheet of elastic material and having aperturesregistering with said openings, conduits within said feed roll eachconnected to one or more of said openings inside of said sheet ofelastic material, and connecting means for sequentially connecting avacuum source to said conduits so that when the openings are in registrywith the hopper the sheet of elastic mate rial is drawn into theopenings to form charge chambers for receiving material from the hopper,the conduits being disconnected from the vacuum source at thedischarge'position to permit the contents of the charge chambers to bedischarged at least in part by the resilience of the sheet of elasticmaterial.

2. Apparatus as claimed in claim 1 wherein said openings are arranged inrows parallel to the axis of rotation of said feed roll, and eachconduit connects the openings in one row.

3. Apparatus as claimed in claim 2 wherein said connecting meanscomprises a valve plate engaging one end of said feed roll and havingmeans for placing each of said conduits in communication with saidvacuum source when the corresponding row of openings is under the mouthof the hopper.

4. Apparatus as claimed in claim 1, further comprising a backing plateengaging the surface of said feed roll at a position between said hopperand said discharge position.

5. Apparatus as claimed in claim 4, wherein said connecting meanscomprises means for releasing the suction while said openings arecovered by said backing plate.

6. Apparatus as claimed in claim 5, further comprising a pressuresource, said connecting means having means for connecting said pressuresource sequentially to said conduits to compress the charge between saidelastic sheet and said backing plate.

7. Apparatus as claimed in claim 4, wherein said backing plate isadjacent said discharge position, and further comprising a flexiblecharge retention sheet positioned preceding said backing plate andattached by one edge to said backing plate.

8. Apparatus as claimed in claim 1, further comprising an elementmovable within each of said openings to limit the depth of penetrationof said elastic sheet.

9. Apparatus as claimed in claim 8, wherein said feed roll includes anaxially movable core, and said elements so engage with said core thataxial movement of said core causes movement of said elements in agenerally radial direction within said feed roll.

10. Apparatus as claimed in claim 9, wherein each element includes agenerally radially-extending rod having a cone-shaped end which engagesin cone-shaped holes in said core.

11. Apparatus as claimed in claim 1 further comprising a Wiper systemwithin said hopper for wiping said sleeve to sweep material into saidopenings.

12. Apparatus as claimed in claim 11, wherein said wiper systemcomprises a plurality of wiper arms, and means for reciprocating saidwiper arms transversely across said sleeve.

References Cited UNITED STATES PATENTS 1,172,603 2/1916 Johnson 222-2252,684,186 7/1954 Mattos 222-368 X 2,792,156 5/1957 Camp 222-309 10ROBERT B. REEVES, Primary Examiner. NORMAN L. STACK, Assistant Examiner.

US. Cl. X.R.

